This invention relates to exercise apparatus, and particularly to apparatus for performing a variation of a stair climbing activity.
Stair climbing exercise apparatus are known. For example, such apparatus is described in Applicant's pending application, Ser. No. 07/934,007 titled Underwater Stair Climbing Exercise Apparatus, the teachings of which are incorporated herein by reference. Typically, the apparatus comprise a pair of horizontal steps mounted for alternate vertical movements, e.g., along a track inclined slightly from the vertical. The steps can be interconnected by means of a cable wound around a pulley at the top of the track, whereby, when one of the steps is driven downward by a user, the other step is pulled up the track. Typically, variable resistance means may be provided for adjusting the amount of force required to move the steps downward. An example of such means is an adjustable brake shoe engaging the pulley driven by the step connecting cable. Another example of such means is extending the surface area of the step.
Stair climbing activates almost all the muscles of the lower limb. In pushing the steps downwards, the most active group of muscles includes the hip extensors, namely the gluteus maximus and hamstring, as well as the knee extensor, namely the quadriceps muscle. The hip flexors are activated to raise the lower limb to the next higher level.
A problem with known stair climbing apparatus is that the degree of exercising of the various muscles is a function of the weight of the exerciser. Stair climbing units on land utilize a computer to compensate for the weight of the exerciser and his weight advantage in pushing the steps down. Similarly, when stair climbing is performed in water, while maintaining an upright position, the weight of the exerciser, though decreased due to the buoyancy of the water, still helps to push the steps down. The use of a computer in underwater apparatus is clearly impractical, and a need thus exists for weight compensation in underwater stair climbing apparatus.